1. Field of the Invention
The present invention relates to a transient voltage suppressor, particularly to a transient voltage suppressor without leakage current.
2. Description of the Related Art
Because the IC device sizes have been shrunk to nanometer scale, the consumer electronics, like the laptop and mobile devices, have been designed to be much smaller than ever. Without suitable protection devices, the functions of these electronics could be reset or even damaged under ESD (Electrostatic Discharge) events. Currently, all consumer electronics are expected to pass the ESD test requirement of IEC 61000-4-2 standard. TVS (Transient Voltage Suppressor) is generally designed to bypass the ESD energy, so that the electronic systems can be prevented from ESD damages.
The working principle of TVS is shown in FIG. 1. In FIG. 1, the TVS devices 10 are connected in parallel with the protected circuits 12 on the PCB (Printed Circuit Board). These TVS devices 10 would be triggered immediately when the ESD event is occurred. In that way, each TVS device 10 can provide a superiorly low resistance path for discharging the transient ESD current, so that the energy of the ESD transient current can be bypassed by the TVS devices 10.
For differential pair line to line application, such as Ethernet, bi-directional TVS with floating ground for ESD protection is necessary because the voltage polarity between two lines can be positive or negative. The schematic is shown in FIG. 2. However, the leakage current of TVS 14 is increased for substrate floating in integrated circuit. Therefore, how to reduce leakage current of TVS device 14 when ground is floating is a challenge.
To overcome the abovementioned problems, the present invention provides a transient voltage suppressor without leakage current, so as to solve the abovementioned problems of the prior art.